Two new collaborators, Elliot Eisenberg, Professor of Engineering at the Pennsylvania State University, and Robert Sarubbi, Professor of Mechanical Engineering and Mechanics at Lehigh University, have joined the Beer and Johnston team for this new edition. Elliot holds a B.S. degree in engineering and a M.E. degree, both from Cornell University. He has focused his scholarly activities on professional service and teaching, and he was recognized for this work in 1992 when the American Society of Mechanical Engineers awarded him the Ben C. Sparks Medal for his contributions to mechanical engineering and mechanical engineering technology education and for service to that society and to the American Society for Engineering Education. Bob holds a B.S. degree in Civil Engineering from the Cooper Union, and a M.S. in Civil Engineering and Ph.D. in Applied Mechanics, both from Lehigh University. After working for five years at Bell Telephone Laboratories on missile systems and design, Bob joined in 1968 the faculty of Lehigh University, where he has specialized in the teaching of system dynamics and design. His research involvement has been in structural mechanics, thermo-fluid systems, and stochastic processes and random vibrations.